Product Description
The CN8478, CN8474A, CN8472A, and CN8471A are advanced Multichannel Synchronous Communication Controllers (MUSYCCs) that format and deformat up to 256 (CN8478), 128 (CN8474A), 64 (CN8472A), or 32 (CN8471A) HDLC channels in a single CMOS integrated circuit. MUSYCC operates at Layer 2 of the Open Systems Interconnection (OSI) protocol reference model. MUSYCC provides a comprehensive, high-density solution for processing HDLC channels for internetworking applications such as Frame Relay, ISDN D-channel signaling, X.25, Signaling System 7 (SS7), DXI, ISUP, and LAN/WAN data transport. Under minimal host supervision, MUSYCC manages a linked list of channel data buffers in host memory by performing Direct Memory Access (DMA) of the HDLC channels.

Distinguishing Features
• 256-, 128-, 64-, or 32-channel HDLC controller
• OSI Layer 2 protocol support
• General purpose HDLC (ISO 3309)
   – X.25 (LAPB)
   – Frame relay (LAPF/ANSI T1.618)
   – ISDN D-channel (LAPD/Q.921)
   – SS7 support
• 8, 4, 2, or 1 independent serial interfaces which support
   – T1/E1 data streams
   – DC to 8.192 Mbps TDM busses
• Configurable logical channels
   – Standard DS0 (56, 64 kbps)
   – Hyperchannel (Nx64)
   – Subchannel (Nx8)
• Per-channel protocol mode selection
   – 16-bit FCS mode
   – 32-bit FCS mode
   – SS7 mode (16-bit FCS)
   – Transparent mode (unformatted data)
• Per-channel DMA buffer management
   – Linked list data structures
   – Variable size transmit/receive FIFO
• Per-channel message length check
   – Select no length checking
   – Select from two 12-bit registers to compare message length
   – Maximum length 16,384 Bytes
• Direct PCI bus interface
   – 32-bit, 66 or 33 MHz operation
   – Bus master and slave operation
   – PCI Version 2.1
• Local Expansion Bus interface (EBUS)
   – 32-bit multiplexed address/data bus
   – Burst access up to 64 Bytes
• Low power, 3.3/2.5 V CMOS operation
• JTAG boundary scan access port
• 208-pin PQFP/surface-mount package
• BGA

APPLICATIONs
• ISDN basic-rate or primary-rate interfaces
• ISDN D-channel controller
• Routers
• Cellular base station switch controller
• CSU/DSU
• Protocol converter
• Packet data switch
• Frame relay switches/Frame Relay Access Devices (FRAD)
• DXI network interface
• Distributed packet-based communications system
• Access multiplexer/concentrator